Solventless low-viscosity alkoxysilyl-functional silicone resins having difunctional and trifunctional siloxane units are known (see U.S. Pat. No. 4,929,691). These liquid alkoxysilyl-functional silicone resins are obtained by hydrolyzing the product from an equilibration reaction between polydimethylsiloxane and methyltrialkoxysilane. While these resins can form water-repellent coatings, their curability cannot be considered satisfactory, and in particular their curability at room temperature is unacceptable.
Compositions comprising, for example, tetraalkoxysilane blended in methyl polysilicate are known as polysilicate-type coating compositions (see Japanese Patent Application Publication (Kokai) No. Hei 3-239774 (239,774/1991)). However, the cured coatings afforded by these compositions exhibit an unsatisfactory water repellency.
An object of this invention is to provide liquid alkoxysilyl-functional silicone resins that exhibit excellent storage stability. Another object of this invention is to provide a method for the preparation of these liquid alkoxysilyl-functional silicone resins. Yet another object of this invention is to provide curable silicone resin compositions that exhibit excellent curability and when cured form a water-repellent coating on a variety of substrate surfaces.